Install TabletMark from the Store, Free.
Charge your battery to 100%.
Disconnect from Power and run TabletMark using the Battery Run Option...
Let the test run until it shuts down. (will take hours)
Charge to 100%/overnight
Repeat one or two times.
After that do it again in a month.
Let it rundown one a month followed by full charge/overnight.
Don't worry, be happy.